Answer from cs61c-eb (Dae-Yeon Kim 16568138) for Question 2
If the block to free is at the end of a list, the freeblock will be combined with the list and leave the number of free blocks unchanged.
So b is right.
The space freed is automatically combined to create a new block, so when a block is freed it may reduce the number of free blocks at the most by one (when the block to free is between two free blocks).
so c is right.